The present invention relates generally to apparatus for flowing fluids into enclosed spaces such as tire interiors. In a preferred embodiment thereof, the present invention more particularly provides a compact, flow through device which sealingly stores a predetermined charge quantity of a liquid, such as a tire sealant liquid or a tire conditioner liquid, and may be subsequently interconnected between the valve stem of a tire, and a source of pressurized air, to efficiently force the entire volume of stored liquid into the interior of the tire as the air continues to inflate the tire.
Various types of aerosol can devices containing a tire sealant liquid are now available to motorists for use in the emergency roadside repair of flat tires. In the typical scenario, the aerosol can is purchased and kept in the vehicle for subsequent use in the event that one of its tires goes flat. When a flat occurs, an outlet fitting on the can may be connected to the flat tire's valve stem to intercommunicate the interiors of the tire and can.
The theory behind this now common aerosol tire repair device is that such intercommunication will force the aerosol propellant into the tire to re-inflate it, and the sealant liquid will be carried into the tire, by the inrushing propellant, to internally seal its puncture or leak. Despite the apparent logic in this theory, in actual practice conventional aerosol tire sealant devices of this general type are commonly subject to a variety of well known problems, limitations and disadvantages.
For example, due to the relatively small volume of these aerosol cans (typically sold in a 16 ounce size) in comparison to the much larger internal volume of the normal automotive vehicle tire, they simply cannot fully re-inflate a flat tire on a car or truck. Typically, they can re-inflate such a tire only to about one third of its normal operating pressure (i.e., to a reinflated pressure of approximately 10 psi.). The result is a grossly underinflated tire which, if driven on for any appreciable distance, can be severely damaged due to such unavoidable underinflation.
The volume disparity between the can and tire also, as a practical matter, limits the use of the can to emergency situations in which the tire is completely flat. Attempts to use the can with a fully inflated tire (i.e., to pre-seal the tire interior), or a tire with a slow leak therein, are normally futile since the can and tire pressures will quickly equalize before much of the sealant can be forced into the tire.
Another problem associated with conventional aerosol tire sealant cans of this type is that it is difficult, if not impossible, to force all of the sealant liquid into the tire due to the relatively high viscosity and volumetric weight of the sealant liquid typically used. What normally happens (particularly if the can is not well shaken before and during use) is that all of the aerosol propellant is discharged from the can before all of the sealant is, thereby often leaving a major portion of the sealant in the otherwise evacuated can.
The outlet of the typical aerosol sealant can is normally provided with a connection fitting which may be threadingly secured to the valve stem. This connection fitting is designed to simultaneously do two things as it is being secured to the valve stem - depress the tire valve closure pin within the valve stem, and open the can's discharge passage for propellant and sealant outflow therethrough into the opened tire valve. It is a common occurrence, however, for the can's discharge passage to be opened before the tire valve is opened. This often results in a messy "sprayback" of sealant onto the user and/or the exterior of the tire being repaired.
A positional problem is also associated with many conventional aerosol sealant cans in that they must be used in an inverted position--i.e., with the can body being disposed generally above the outlet of the can. Because of potential interference between the inverted can body and the wheel well portion of the car or truck body, this typically and often inconveniently requires that the still-mounted flat tire be rotated until its valve stem is positioned on a lower portion thereof.
From an environmental standpoint, aerosol tire sealant cans of this type are, of course, also undesirable. At some point in time the aerosol propellant delivered into the tire interior will be freed to further damage the environment. Furthermore, as is well known, the typical aerosol propellant is highly flammable, thereby creating a potential fire hazard if appropriate care is not taken during its use.
Finally, for a rather interesting psychological purpose, a substantial quantity of water is typically placed in the cans along with the sealant and propellant therein. The purpose of this water addition is simply to add weight to the overall device so that a consumer, when picking the can up in a store, will not think the can is too light (and therefore empty) and place it back on the shelf. The added water serves no other useful purpose.
At least part of this water is ultimately injected into the interior of the tire being repaired, thereby undesirably creating several potential problems. For example, the injected water can cause deterioration of the interior surface of the tire, and can accelerate rusting of the metal wheel rim. Additionally, during cold weather the injected water can freeze, thereby creating tire imbalance.
At least some of these problems also exist in other applications in which it is necessary to force a treatment liquid into an enclosed space through an inlet valve operatively associated therewith - for example, the injection into an air conditioning system refrigerant circuit of a leak inhibiting liquid.
From the foregoing it can readily be seen that a need exists for improved apparatus for injecting sealant or other treatment liquid into the interior of a tire or other enclosed space. It is accordingly an object of the present invention to provide such improved apparatus.